The electroencephalographic features of the sleep onset process and their experimental manipulation with sleep deprivation and transcranial electrical stimulation protocols

The Regional EEG Pattern of the Sleep Onset Process in Older Adults

“…To the best of our knowledge, this is the first complete description of the spatiotemporal EEG pattern during the SO in a group of older adults. Beyond confirming the main electrophysiological features previously observed in the wake-sleep transition of young adults [22,23], we found several peculiarities in the elderly: (a) the generalized post-SO power increase in the slowest frequencies (i.e., delta-theta range) did not encompass the 7 Hz bin; (b) alpha power revealed a complex frequency-specific pattern of significant post-SO modifications; (c) sigma activity exhibited only a slight post-SO increase, and the highest bins in this frequency range also showed a frontotemporal power decrease.…”

“…In this field of knowledge, one of the missing pieces is represented by the effect of physiological aging on the spatiotemporal EEG dynamics of the sleep onset (SO), the complex and progressive transitory process between wakefulness and sleep [20,21]. From an electrophysiological standpoint, the wake-sleep transition in healthy young adults is characterized by extensive modifications [22,23], mainly consisting of (a) an orchestrated pattern of regional and gradual frequency-specific changes observable from the scalp EEG recordings [24][25][26][27], (b) asynchronies in the EEG pattern of cortical and deep brain structures [28,29], and (c) marked changes in cerebral dynamic interactions [30][31][32][33]. Moreover, the electrophysiology of the falling asleep process is modulated by the level of homeostatic sleep pressure [33][34][35][36][37].…”

Age-Related Effect of Sleepiness on Driving Performance: A Systematic-Review

“…However, this investigation showed increased theta activity during driving in older adults, that may reflect a local sleep phenomenon [62,63]. Indeed, in previous studies on young samples, both alpha and theta power show specific patterns during the wake-sleep transition [61]. The theta activity exhibits a fronto-central maximum peak before and after sleep onset.…”

“…Further, alpha power, as an expression of objective sleepiness [61], was higher in the younger group during the lighted motorway condition. However, this investigation showed increased theta activity during driving in older adults, that may reflect a local sleep phenomenon [62,63].…”

Sleep-Based Interventions in Alzheimer’s Disease: Promising Approaches from Prevention to Treatment along the Disease Trajectory

“…Different behavioural and physiological modifications can be obtained depending on the specific stimulation parameters, such as stimulation site, location of the reference, duration, waveform, frequency, polarity, and intensity. A growing body of evidence shows that tCS techniques can induce changes in sleep electrophysiology [180] and several findings suggest that these procedures may represent valid candidates to bidirectionally affect sleepiness levels and the electrophysiological processes that characterize sleep onset [180,181]. Crucially, several tCS protocols applied during sleep can enhance NREM sleep oscillations and, in turn, promote memory consolidation in healthy subjects [182][183][184][185][186].…”